Whatever the damage in world tensions, a Soviet move into Poland would likely strengthen President Reagan's standing with the American people. Mr. Reagan is expected to follow the Eisenhower precedent of 1956 when the Soviets invaded Hungary -- condemn the invasion but take no military steps -- experts on the US presidency assume. President Eisenhower's prestige soared as he was viewed as being strong, but peace-preserving, and he easily won reelection that fall.
Among the US domestic implications of a Soviet move into Poland, assuming the crisis would be contained within the East bloc, as seen by White House experts and political strategists here:
* Reagan is forced to delegate crisis-management duties heavily, but his recovery from his wound apparently is rapid enough for him to play a helmsman's role.
* Momentum for the administration's economic program in Congress is seen as great enough to withstand a diversion of focus to Soviet-Polish events.
* A deepened Polish crisis would mean a longer hold on the Soviet grain embargo, testing the patience of American farmers. So far, however, grain prices for farmers have been buoyed by drought-shrunken crops at home and demand abroad.
"A Soviet invasion of Poland would be viewed by Americans as an affirmation of the Reagan view of the world -- that the Soviets are the real threat, intent on overthrowing governments," says Stephen Wayne, a George Washington University political scientist.
"There's not much the US can do," Mr. Wayne says. "We hear about military aid for the Chinese, or pressuring Europe to build up NATO forces."
However, limits on the ability of the United States to respond would not damage Reagan personally, despite his campaign promises to show greater strength abroad, Wayne and other experts say.
While Americans want a stronger military, the memories of Vietnam remain vivid enough for Americans to hesitate at committing US troops abroad. The mood is seen as similar to the post-Korean conflict and the invasion of Hungary.
"Eisenhower just shrugged his shoulders at the hopelessness of doing anything about the Hungary invasion," says Fred Greenstein, a Princeton University authority on the Eisenhower White House. "Nobody wanted to commit American troops in Eastern Europe, just four years after Korea. The public viewed Hungary more in terms of Soviet aggression than American inaction."
Harvard presidential historian Frank Freidel calls the Eisenhower-Hungarian precedent "a very good one" for the Reagan-Polish crisis.
"On the one hand, Eisenhower gave the impression of taking a strong national stand, protecting the national interest," says Mr. Freidel. "At the same time, for all the talk of rolling back communism during Eisenhower's own campaign --[ Secretary of State John Foster] Dulles talked of 'liberation' rather than 'containment' -- he didn't really do anything.
"With the Vietnam war behind us now, if Reagan makes strong disapproving noises, as he has been making, and continues the grain embargo, but does nothing really that could push the Soviet troops out of Poland -- and there's nothing he can do, short of war -- he's going to be in much the same popular position as Eisenhower."
Reagan already is benefiting from his "great personal courage at the time of the assassination attempt," Freidel says."And public opinion will likely rally even more to him when he states vigorously what he thinks about the Polish situation."
Michael Barone, a Democratic pollster and strategist, sees Reagan's standing likely enhanced by a Soviet test in Poland.
"He's going to be in the posture of expressing the views and attitudes of a majority of the American people," Mr. Barone says. "The public doesn't think his rhetoric promised a rolling back of the Soviets from Eastern Europe. He's expressing the feeling of Americans who don't want to see the Russians in there to a greater extent than they are."
President Carter suffered in public standing over the Soviet incursion into Afghanistan because "many opposition politicians and analysts felt the Carter policies had invited the Soviets to do that," Barone says. "And there was a feeling it was an advance of Soviet power, rather than a maintenance of Soviet power."
The Reagan economic program may no longer require the daily public attention the administration has sought to focus on it, Barone says, observing that a crisis in Poland would not give the Democrats a cover for inaction.
"The Republicans are in darn good shape on these things," Barone says. "They've framed the issue: Are you going to cut $49 billion off the budget, or aren't you? Are you going to make some cuts in a wide range of federal programs , or are you going to have things as they are? The public comes down on their side."